A 3D-Printed Micro-Solid-Phase Extraction Device with Hypercrosslinked Polystyrene Sorbents for Highly Reproducible Aromatic Acid Analysis in Blood Serum.

Modern methods for preparing biological samples prior to chromatography-mass spectrometry analysis are rapidly developing and include both commercial platforms and in-house devices designed for specific sample-preparation conditions. Here, we demonstrate the feasibility of using hypercrosslinked polystyrene, packed into disposable plastic pipette tips, as a sorbent for micro-solid-phase extraction. This approach was combined with a custom 3D-printed device designed to perform sample preparation similar to that of commercial microextraction by packed sorbent (MEPS) systems. Extraction conditions were developed for aromatic metabolites of tyrosine and phenylalanine in human blood serum, followed by gas chromatography-mass spectrometry analysis of their silyl derivatives. The proposed method was evaluated using serum samples from healthy donors. Two types of hypercrosslinked polystyrene with nominal particle sizes of 40 and 60 µm were used. Under the optimized conditions, the mean normalized recoveries reached 90% for benzoic acid and 60-80% for most analytes, whereas phenyllactic and 4-hydroxyphenyllactic acids, the two most polar analytes, remained at lower recoveries. Moreover, the 3D-printed device achieved reproducibility comparable to that of a commercial MEPS system, with relative standard deviations below 10% under optimized conditions. The proposed in-house device also offers a fast and efficient strategy for evaluating custom sorbents in various sample-preparation applications.